I was with Ibn `Umar on the way to Mecca, and he got the news that Safiya bint Abu Ubaid was
seriously ill. So, he hastened his pace, and when the twilight disappeared, he dismounted and offered
the Maghrib and `Isha' prayers together. Then he said, "I saw that whenever the Prophet (ﷺ) had to hasten
when traveling, he would delay the Maghrib prayer and join them together (i.e. offer the Maghrib and
the `Isha prayers together).
Sahih al-Bukhari Book 26, Hadith 30